Activity fee is different than the booster fee.  Activity fee is paid to the school one time a year.  The fee for 2019-20 is $50.  Pay it online when you sign up with Family ID.

https://s3-us-west-2.amazonaws.com/sportshub2-uploads-prod/files/sites/2322/2020/01/23112620/Spring-Sports-Registration-and-Physical-Information.pdf